Preferred 64 bit Browser: FireFox, WaterFox, Vivaldi, Opera...or

I have been looking for a different browser, having spent the better part of the year using Waterfox, with prior experience with Opera, Vivaldi, Opera, Edge and IE. I am currently using the 64 bit version of FF and have been happy thus far. The available apps and the ability to configure both FF and WF are nice. However, I know there are other browsers to choose from, perhaps some I've never heard of. The goal is to learn who's using what and why, which will either confirm my browser choice or introduce a new, better browser without having to install/uninstall them all. I am not asking, "what's the best 64 bit browser" for Win 7 because the answer is mainly one's preference. It also avoids parsing benchmark data looking for differences on a scale of 10^ -4.

Therefore, using: Security, Speed, and Stability as the primary criteria, (configurability and other criteria not excluded) what is your preferred - General Use - 64 bit browser and why?